A cadenza is an extended passage at the final cadence of a concerto movement for a soloist to show off his or her improvising skills; the orchestra stops on an unresolved chord and the performer sets off alone on an often prolonged virtuoso display ending in a trill to summon the orchestra for the final resolution. Cadenzas first featured in 18th-cent. Neapolitan opera arias and string works of Corelli and Vivaldi, whence classical composers adopted the idea. For the ‘Emperor’ concerto Beethoven wrote the cadenzas as part of the whole and inspired 19th-cent. composers and performers to make the cadenza an opportunity to pre-compose elaborate fantasies based on thematic material from the work — Amanda Holden